1. Field of the Invention
The invention relates in general to keyboards and in particular to curved keyboards with improved structural strength.
2. Description of the Related Art
Referring to FIG. 1, a conventional wave-shaped keyboard primarily comprises a main body M and a plurality of key units 10. Each of the key units 10 includes a first rod 101, a second rod 102 and a key cover 103. The main body M includes a top frame 20, a curved substrate module 300, a support member 40, a circuit board 50, a base plate 60, and a bottom frame 70. The top frame 20, the base plate 60, and the lower frame 70, are joined to hold the keyboard. The curved substrate module 300, support member 40, and circuit board 50 are disposed over the base plate 60 and encompassed by the top and bottom frames 20 and 70.
As shown in FIG. 1, the substrate module 300 has a plurality of holes H and pivot portions P rotatably connected to the first and second rods 101 and 102. A plurality of elastomers 401 project from the support member 40 and pass through the holes H. When the key covers 103 are depressed, the elastomers 401 are deformed downward to activate corresponding switches (not shown) on the circuit board 50.
Generally, the top frame 20 is plastic, and the substrate module 300 is metal. The holes H and pivot portions P can be shaped by mechanical stamping and punching. However, the substrate module 300 may not provide good structural strength for the keyboard due to flexibility of metal. Moreover, unintentional impacts on the protrusive pivot portions P during assembly may cause deformation and damages of the metal substrate module 300.